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<a name="building.background"></a><a class="link" href="background.html" title="Background">Background</a>
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<p>
        There are two basic models for combining C++ and Python:
      </p>
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<li class="listitem">
            <a href="http://www.python.org/doc/current/ext/intro.html" target="_top">extending</a>,
            in which the end-user launches the Python interpreter executable and
            imports Python “extension modules” written in C++. Think of taking
            a library written in C++ and giving it a Python interface so Python programmers
            can use it. From Python, these modules look just like regular Python
            modules.
          </li>
<li class="listitem">
            <a href="http://www.python.org/doc/current/ext/embedding.html" target="_top">embedding</a>,
            in which the end-user launches a program written in C++ that in turn
            invokes the Python interpreter as a library subroutine. Think of adding
            scriptability to an existing application.
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<p>
        The key distinction between extending and embedding is the location of the
        C++ <code class="computeroutput"><span class="identifier">main</span><span class="special">()</span></code>
        function: in the Python interpreter executable, or in some other program,
        respectively. Note that even when embedding Python in another program, <a href="http://www.python.org/doc/current/ext/extending-with-embedding.html" target="_top">extension
        modules are often the best way to make C/C++ functionality accessible to
        Python code</a>, so the use of extension modules is really at the heart
        of both models.
      </p>
<p>
        Except in rare cases, extension modules are built as dynamically-loaded libraries
        with a single entry point, which means you can change them without rebuilding
        either the other extension modules or the executable containing <code class="computeroutput"><span class="identifier">main</span><span class="special">()</span></code>.
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<td align="right"><div class="copyright-footer">Copyright © 2002-2015 David
      Abrahams, Stefan Seefeld<br>Copyright © 2002-2015 David Abrahams, Stefan Seefeld<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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